The present invention relates to an electronic house arrest monitoring (EHAM) system, and more particularly to a particular type of field monitoring device (FMD) used in such an EHAM system that cannot be altered or reprogrammed except by authorized personnel.
An EHAM system is a particular type of electronic monitoring system that electronically monitors a predefined area for the presence of a particular individual. Typically, the predefined area is the residence and/or work place of the individual. The individual being monitored is usually a person who has been convicted of a crime and sentenced to a specific term of incarceration, or is on probation. Sometimes the person being monitored has already served a sentence and is on parole, but must report in at regular intervals to a parole officer. Because the monitored individual has normally been convicted of some type of offense, such monitored individual is hereinafter referred to as an "offender".
Advantageously, EHAM systems allow many incarcerated offenders to serve part or all of their sentence outside of a normal detention facility. Thus, rather than serving their sentence in an overcrowded jail or prison, the offender is simply sentenced to remain at a specified location, such as his or her house, under "house arrest". The EHAM system advantageously monitors the specified location to assure compliance with the house arrest order, and immediately reports any detected violations of the house arrest order to the appropriate officials.
Moreover, EHAM systems allow probation officers, and others charged with the responsibility of assuring compliance with a particular sentence, probation or parole requirement, to more easily monitor a relatively large group of offenders for compliance with their respective house arrest requirements.
Electronic monitoring systems thus fulfill a valuable need in that they allow a relatively large number of individuals, who have been ordered by a court to remain under house arrest, or who are under specific parole or probation requirements, to be electronically monitored for compliance with whatever restrictions have been imposed. Such electronic monitoring can advantageously be carried out at a fraction of the cost of incarceration of the monitored individuals, and also at a much reduced cost compared to conventional probation/parole monitoring procedures.
One type of EHAM system known in the art, referred to as an "active" monitoring system, generates and transmits radio wave signals as part of the monitoring process. Such an active EHAM system is described, e.g., in U.S. Pat. No. 4,918,432, issued to Pauley et al., which patent is incorporated herein by reference. In the Pauley et al. EHAM system, each offender being monitored is fitted with an electronic bracelet or anklet. Such bracelet or anklet, referred to in the referenced patent as a "tag", includes a transmitter that periodically transmits an identifying radio wave signal (unique to each tag, and hence to each offender) over a short range (e.g., 150 feet). A field monitoring device (FMD) is installed at each where the monitored offender(s) is supposed to be. If the monitored offender(s) is present at the FMD location, a receiver circuit within the FMD receives the unique identifying signal. Processing circuits within the FMD determine if the received identifying signal is a valid signal assigned to a particular offender. The FMD processing circuits can thus determine whether a specific offender is present at the location of the FMD when the signal is received. This information is stored within the FMD memory circuits for subsequent downloading to a central monitoring location.
A computer, or central processing unit (CPU), located at the central monitoring location (which location is typically remote from the FMD location), periodically or randomly polls the various FMD locations through an established telecommunicative link, e.g., through standard telephone lines, in order to prepare reports indicating the presence or absence of the offenders at the specified locations. Such reports are then used by the agency charged with the responsibility for monitoring the offenders to ascertain whether or not such monitored offenders are in compliance with whatever restrictions have been imposed.
An important feature of the Pauley et al. EHAM system is the ability of the tag to detect any attempts to tamper with it, e.g., attempts to remove the tag from the monitored offender. If a tamper event is detected, such occurrence is signaled to the FMD in the next identifying signal that is transmitted; and the FMD, in turn, includes the ability to establish telecommunicative contact with the central CPU in order to report such tamper event. All data sent from the FMD to the central CPU includes address-identifying data that identifies the specific location where the FMD is located.
Other active EHAM systems known in the art also include the ability to detect tamper events, such as U.S. Pat. No. 4,777,477, issued to Watson, wherein any attempt to cut or break the strap that attaches the tag to the individual is detected and signaled to a local receiver.
Still additional active EHAM systems known in the art include the ability to adaptively change the monitoring configuration to best suit the needs of the agency responsible for carrying out the monitoring function. See U.S. Pat. No. 4,952,928 issued to Carroll et al., also incorporated herein by reference. The Carroll et al. system advantageously includes the ability to sense and monitor various physiological data of the monitored individual, such as heart rate, blood pressure, body position (horizontal or vertical), and the like, so that such data can be analyzed at the central monitoring location to determine if the monitored individual is complying with other restrictions, such as abstinence from drugs or alcohol.
Another type of EHAM system known in the art, typically referred to as an "passive" monitoring system, requires the offender being monitored to perform some act, such as inserting a specially configured, non-removable, wristlet into a decoder device, in order to verify his or her presence at the remote monitoring location. The decoder device, which may be considered as the equivalent of the FMD, then telecommunicatively communicates with a CPU at a central monitoring location in order to report that the presence of the offender was successfully detected. See, e.g., U.S. Pat. No. 4,747,120.
Regardless of the type of EHAM system used --passive or active--there is a need for a given level of environmental security associated with the installation and use of an FMD or equivalent device. The FMD includes certain electronic processing circuitry, typically realized using at least one microprocessor circuit coupled to appropriate memory circuits, that controls the monitoring function. The FMD also includes, in its memory circuits, programmable operational parameters that are critical to the monitoring process. Although it is necessary to provide a means of communicating with the FMD to inspect and/or change its operational parameters, it is imperative that access to these operational parameters, and to the memory circuits in general, be secure and accessible only to authorized individuals. At no time should the monitored offender be allowed access to the FMD memory circuits.
Unfortunately, with a remote unmanned monitoring system such as an EHAM system, there is always the risk that the offender may try to thwart the system. That is, the offender may try to disable or modify the functions of the FMD through any means possible. Such approaches may include, but are not limited to, introducing dangerous voltages to exposed connector contacts, shorting exposed contacts with metallic objects, disconnecting power and telephone lines, etc. What is needed, therefore, is an FMD that is tamper proof, and that is immune to all such attempts to thwart its proper operation.
Moreover, it is not uncommon for a particular offender to have a working knowledge of personal computers, and/or popularly used data communication systems and protocols. Such an offender may thus be tempted to tamper with the FMD, and more particularly to interfere with the transfer of data between the FMD and CPU at the central monitoring location, and/or to "reprogram" the FMD so that it operates incorrectly, thereby causing the FMD to provide false information to the central monitoring location. If the FMD employs conventional data communication schemes and protocols, the ease with which such tampering could be accomplished is significantly enhanced. Thus, there is a need in the art for a more secure data transfer link between the FMD and the CPU, as well as a more secure method of accessing and programming an FMD. In particular, there is a need for a secure FMD programming technique or method that cannot be ascertained through a physical inspection of the FMD, and that is accessible and usable only by authorized personnel.
Further, even for individuals who are authorized to gain access to the FMD's operational parameters, not all such authorized individuals need access privileges to the same set of operational parameters. Thus, for example, an installer who installs an FMD in the field may only need access to a limited subset of operational parameters. An authorized factory representative, on the other hand, may need access to all operational parameters. Hence, there is a need in the art not only to limit access to the FMD's operational parameters to authorized personnel, but also to provide different levels of access to different types of authorized personnel.